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Questions tagged [unsafemutablepointer]

116 questions
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How to use UnsafeMutablePointer in swift 4

Objective-c has a concept of a pointer to a pointer. If you dereference the first pointer you can access the original void makeFive(int *n) { *n = 5; } int n = 0; makeFive(&n); // n is now 5 When this is bridged to Swift 3 it becomes an…
DerrickHo328
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Swift: Cannot convert value of type 'UnsafeMutablePointer' to expected argument type 'UnsafeMutablePointer'

I have a little Problem with my Code after updating to Swift 3. I had this Code before the conversion: extension NSData { func castToCPointer() -> T { let mem = UnsafeMutablePointer.alloc(sizeof(T.Type)) self.getBytes(mem, length:…
Luke Pistrol
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How to cast UnsafeMutableRawPointer! to UnsafeMutablePointer in Swift 3.0 or newer?

I am working with Accelerate library for my iOS app. I built this app in Swift 2.0 a couple years ago and it was working fine. Now that Swift is updated to 3.0 and 4.0, I have to convert most of the code to the current syntax. I have run the…
Keen R.D.
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Pointers in Swift

I'm trying to understand the use of pointers in Swift, in particular: Unsafe[Mutable]Pointer and UnsafeRaw[Mutable]Pointer. I have several questions on the subject. Is UnsafePointer equal to const T * Pointer in ? and UnsafeMutablePointer …
emacos
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Convert UnsafeMutablePointer to UnsafePointer

I'm using a C library in my Swift project, and one of functions requires a UnsafePointer?>! as an in-out argument where I should pass my data. But the problem is that I have this data in…
Eugene Alexeev
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How to convert array to UnsafeMutablePointer Swift 3.0?

Here was my workable code in the previous version of Swift: let imageOptionsDictKeys = [ kCVPixelBufferPixelFormatTypeKey, kCVPixelBufferWidthKey, kCVPixelBufferHeightKey, kCVPixelBufferOpenGLESCompatibilityKey,…
JULIIncognito
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UnsafeMutablePointer in Swift 3

I'm attempting to call SecItemCopyMatching in my keychain utility class in order to get data out of the keychain, yet I'm running into a problem with getting the result argument, UnsafeMutablePointer. The original statement (in Swift 2,…
Jojodmo
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UnsafeMutablePointer.pointee and didSet properties

I got some unexpected behavior using UnsafeMutablePointer on an observed property in a struct I created (on Xcode 10.1, Swift 4.2). See the following playground code: struct NormalThing { var anInt = 0 } struct IntObservingThing { var…
kid_x
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Swift UnsafeMutablePointer: Must I call deinitialize before deallocate?

Given an instance of UnsafeMutablePointer, what's the point of calling deinitialize(count:) right before deallocate(capacity:)? Can't you just call deallocate(capacity:)? I saw this when reading the section "Using Typed Pointers" of the article…
ma11hew28
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Testcase failed after converting codes from Objective-C to Swift

I am doing some bitwise operations in Swift style, which these codes are originally written in Objective-C/C. I use UnsafeMutablePointer to state the beginning index of memory address and use UnsafeMutableBufferPointer for accessing the element…
Zigii Wong
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UnsafeMutablePointer to an Array element

var a = [1,2,3] let ptr1 = UnsafeMutablePointer(&a[0]) //works fine let index = 0 let ptr2 = UnsafeMutablePointer(&a[index]) //compiler throws error error: cannot invoke initializer for type UnsafeMutablePointer with an argument…
jblixr
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Why a struct declared by let can be changed?

In the following code, 'ptr' is a struct declared by let, but its member variable 'pointee' could be changed, Why? let ptr = UnsafeMutablePointer.allocate(capacity:1) ptr.pointee = 1
Laughing
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Swift deallocate vs free usage

I am allocating bytes using the following call in Swift 3: let wordSize = 2 let numbytes = 1024*wordsize var ptr = UnsafeMutableRawPointer.allocate(bytes: numbytes, alignedTo: wordSize) Question is whether it is correct to deallocate the memory,…
Deepak Sharma
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Mutual non-optional reference cycle in Swift

Consider the following use case: In a model for some game, you have a Player class. Each Player has an unowned let opponent: Player which represents the opponent they are playing against. These are always created in pairs, and a Player must always…
Jumhyn
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Using C functions in Swift that take functions as arguments

I'm writing a wrapper around a C mathematical library. Every function takes one or two functions as arguments. However, the arguments for those child functions (as well as the parent functions) are not Swifty -hence the wrapper. I've cleaned up the…
Adam Jones
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